This invention relates to disposal of light hydrocarbons, e.g., waste organic solvents. More particularly, this invention relates to processing light hydrocarbons with a heavy oil to produce a product which has a higher flash point and is useful as a fuel.
Light hydrocarbons used as solvents in industrial processes, such as textile treating, polymer coating, printing, and other processes, generally become contaminated during use. In many instances, it is not practical to repurify the solvents. Instead, the solvents are merely discarded. Due to the hazardous nature of such materials, special handling is necessary. In most instances it is necessary for industrial concerns desiring to dispose of waste solvents to pay scavengers to remove the solvents to secure landfills or approved incinerators.
Waste solvents are generally highly combustible, highly contaminated and have low flash points. Typical waste solvents have an open cup flash point according to ASTM Standard D-1310-72 below normal room temperature, often as low as -10.degree. C. Such materials are unsuitable for direct use as a boiler fuel because their low flash point indicates an excessively high degree of vaporization will occur in the furnace which would inhibit control of the combustion necessary to achieve smooth, safe operation of the boiler. It is generally held that safe, controlled combustion can be achieved only when the flash point of the fuel is no less than about 40.degree. to 45.degree. C. (approximately 110.degree. F.). Consequently, waste solvents cannot be utilized directly as a fuel for most applications.
Attempts have been made to combine light hydrocarbons and heavy oils to produce useful fuels. Simple mixing of solvent and oil will increase the flash point somewhat. A one to one mixture of waste solvent having a flash point of about -10.degree. C. with No. 6 fuel oil has a flash point of about 18.degree. C. (65.degree. F.) when kept well mixed. However, such mixtures ordinarily separate upon standing so that the low flash point of the solvent will again be encountered. Hays, U.S. Pat. No. 1,416,291, discloses treating a mixture of heavy hydrocarbon, wood alcohol and light hydrocarbon in the vapor phase at elevated temperatures with an aluminum-rich burned clay catalyst mixed with zinc and nickel to produce a fuel mixture. Curtis, U.S. Pat. No. 4,318,623, discloses mixing high volatility combustible fuels with heavy oils using a static mixer. Despite claims by Curtis that his product is stable, simple mixtures of ingredients tend to segregate upon standing for an extended period of time. There remains a need for an improved process and apparatus which can be used to dispose of waste solvents and the like.